JUDY WOODRUFF: Tonight: an exclusive story from Iraq on American citizens, civilians, fighting the Islamic State group. Many are former U.S. military, but some have never seen a battle before.
Special correspondent Marcia Biggs reports.
MARCIA...

Watch VideoGWEN IFILL: Patients, advocates and scientists are hailing new studies that show the value of getting AIDS drugs to people early and often.
The three-decade-long fight against AIDS has seen a series of breakthroughs in recent weeks,...